FACTORS INFLUENCING THE COMMUNITY  STRUCTURE  AND  DISTRIBUTION  OF
ZOOPLANKTON IN LAKE CHAUTAUQUA

Kristy C. Boggs 1, 2, James A. Stoeckel 1, and Richard V. Anderson 2.
1 Illinois Natural History Survey, Long Term Resource Monitoring Program, Havana 
Field Station, 704 North Schrader Avenue, Havana, IL 62644; and 2 Department of 
Biological Sciences, Western Illinois University, 1 University Circle, Macomb, IL 
61455.

Lake Chautauqua is a backwater lake of the Illinois River near Havana, IL.  It is divided 
by a cross dike into northern (Kikunessa) and southern (Wasenza) pools and is 
managed by the US Fish and Wildlife Service as part of the Illinois River Refuges.  In 
1992 it was selected as a site for a Habitat Rehabilitation and Enhancement Project 
(HREP) by the Environmental Management Program for the Upper Mississippi River 
System.  As part of the HREP the Illinois Natural History Survey conducted a study of 
the larval fish production in the Wasenza Pool.  Zooplankton in Wasenza Pool were 
examined to determine the food base available to larval fish.  This study is a more 
detailed look at the zooplankton community that was examined for the HREP study. 
In this study we determined the community structure and how it changed throughout 
the season.  We then attempted to correlate these changes to changes in 
environmental factors such as water temperature, dissolved oxygen, turbidity, water 
depth, and degree of connection between the lake and river to determine what effect, 
if any, these factors have on community structure.  Three fixed sites were established 
in open water areas of the lake and zooplankton was sampled weekly from 4-21-98 
to 7-27-98.  These samples were counted and identified during the summer of 1999. 
Rotifers and cladocerans were identified to at least the genus level and in many cases 
to species.  Copepods were identified to suborder.  The density and diversity of 
zooplankton for the entire limnetic portion of the lake was determined by averaging 
the 3 sites together.  During analysis of samples it was noted that on some dates 
there were great differences in abundance between sites.  The previously mentioned 
factors and larval fish distribution are currently being examined to determine if any of 
these factors are responsible for the differences between sites.

Keywords:  zooplankton; Lake Chautauqua, backwater lake, Illinois River
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